New research reveals that hippos survived in central Europe much longer than previously believed, persisting in Germany's Upper Rhine Graben until about 31,000 years ago. Ancient DNA and radiocarbon dating show these animals coexisted with mammoths during a milder phase of the last ice age. The findings challenge earlier timelines of hippo extinction in the region.
Hippos, typically associated with sub-Saharan Africa, roamed central Europe far longer than scientists once thought. A study published in Current Biology indicates that the common hippopotamus (Hippopotamus amphibius) lived in the Upper Rhine Graben of southwestern Germany between approximately 47,000 and 31,000 years ago, well into the middle of the last ice age.
Previously, researchers believed hippos had vanished from central Europe around 115,000 years ago, at the end of the last interglacial period. However, an international team led by the University of Potsdam, in collaboration with the Reiss-Engelhorn-Museen Mannheim and the Curt-Engelhorn-Zentrum Archäometrie, analyzed fossils from gravel and sand layers in the region. These bones provided well-preserved samples for analysis.
"It's amazing how well the bones have been preserved. At many skeletal remains it was possible to take samples suitable for analysis -- that is not a given after such a long time," said Dr. Ronny Friedrich, a specialist in age determination at the Curt-Engelhorn-Zentrum Archäometrie.
Ancient DNA sequencing confirmed that these Ice Age hippos belonged to the same species as modern African populations and were closely related to them. Radiocarbon dating placed their survival during a warmer phase of the middle Weichselian glaciation. Genome analysis revealed low genetic diversity, indicating a small, isolated population. Notably, these warm-adapted hippos shared habitats with cold-climate species like mammoths and woolly rhinoceroses, underscoring the diverse ecosystems of the Ice Age.
"The results demonstrate that hippos did not vanish from middle Europe at the end of the last interglacial, as previously assumed," said first author Dr. Patrick Arnold. "Therefore, we should re-analyze other continental European hippo fossils traditionally attributed to the last interglacial period."
Prof. Dr. Wilfried Rosendahl, director of the Reiss-Engelhorn-Museen Mannheim and leader of the "Eiszeitfenster Oberrheingraben" project, added: "The current study provides important new insights which impressively prove that ice age was not the same everywhere, but local peculiarities taken together form a complex overall picture -- similar to a puzzle. It would now be interesting and important to further examine other heat-loving animal species, attributed so far to the last interglacial."
The project, supported by the Klaus Tschira Stiftung Heidelberg, examines climate and environmental changes in the Upper Rhine Graben over the past 400,000 years using bones from the Reis collection.